MONDAY, June 9, 2014 (HealthDay News) -- Teenage bullies and their victims are more likely to carry weapons than kids not involved in these abusive relationships, according to a new research review.

With school shootings a concern across the United States, the findings -- culled from 45 previously published studies -- put a spotlight on the potential link between bullying and subsequent violence, experts said.

"Bullying was already found harmful for victims in previous studies, but bullying may also be related to a more unsafe atmosphere in school for all attending children and the personnel through an increased likelihood of weapon carrying," said the lead researcher of the study, Mitch van Geel of the Institute of Education and Child Studies at Leiden University in the Netherlands.

"Adolescents who carry weapons are more likely to get into fights, to suffer injury, and to experience hospitalization than adolescents who do not carry weapons," van Geel said.

The analysis found that bullies, victims and bully-victims -- kids who are picked on who then become bullies themselves -- were more likely to carry weapons than others.

And bully-victims were more likely to carry weapons than victims, especially in the United States, where guns are more accessible, the researchers noted. One study found that bully-victims were also more likely to report using a weapon than victims.

However, the research doesn't prove that bullying causes teens to take up arms, or explain why they might do so, van Geel said. Still, "reducing bullying may reduce weapon-carrying among adolescents," he said.

"It may be that victims carry weapons to protect themselves," he said. "Bullies might carry weapons in order to threaten or intimidate others, or as part of an underlying aggressive personality that affects both bullying and weapon-carrying." And bully-victims may carry weapons both for protection and/or intimidation, he said.

The analysis included 22 studies of victims of bullying, 15 studies of bullies and eight studies of bully-victims. In all, the research involved more than 692,000 people ages 11 to 21.

Experts disagree on the significance of the findings, published June 9 online in JAMA Pediatrics.

Stephen Russell, of the University of Arizona in Tucson, said the results confirm it is the combination of being bullied and being a bully that is "clearly linked to weapon carrying and thus the potential for serious harm in schools."

Studies of school shooters reveal the same pattern, said Russell, director of the university's institute for family studies and human development. "They are generally boys who were both bullies, and relentlessly bullied," he said.

"To see this pattern borne out across multiple large-scale studies is very important to confirm that we need to pay careful attention to this potentially lethal combination -- of bullying and being bullied," Russell said.

But Madelyn Gould, deputy director of research training in child psychiatry at Columbia University Medical Center in New York City, said the study has shortcomings.

"Although we have to be concerned about bullying, this study doesn't provide reliable evidence that if someone has been identified as a bully or bully-victim they have to be assessed to see if they are carrying weapons," Gould said.

"The vast majority of young people are not carrying weapons," she added. "To assume that they are, based on this study, could lead to consequences we didn't want. You don't want to create more of a stigma that all of these kids are going to be a danger to the larger community."

Dr. Thomas Paul Tarshis, director of the Bay Area Children's Association in Cupertino, Calif., believes a "culture shift" is needed to deal with bullying in the United States.

"We have this broken mental health system and also a broken system around recognizing and helping bullies and victims in schools," he said.

Tarshis thinks that solving the bullying problem needs to start in elementary schools. Most schools only pay lip service to bullying, with an assembly or assigning a book about bullying, he said.

"There are very few districts that have taken a community-wide approach to address bullying, and that's what needs to happen," Tarshis said.

Bullies, victims and bully-victims who carry weapons need help from mental health professionals, he said.